以功率轉換研究65 nm nMOSFET之高溫熱載子交直流壽命

眾所週知，晶圓廠作熱載子可靠度測試時，大都是在直流(DC)下作定電壓應力(constant voltage stress, CVS)使元件特性提早劣化，並進一步評估其壽命，原因是為了縮短測試與評估元件良率的時間。然而，元件在CMOS電路操作上卻是處於交流(AC)狀態下，如何準確預測AC狀態下元件壽命則是一重要的問題。在本實驗中，我們使用測試元件來自UMC的65奈米製程的nMOSFETs元件。對通道長度/寬度(W/L)=1/0.05(μm/μm)的元件，進行DC及AC的通道熱載子(channel hot-carrier, CHC)實驗。所有測試分別以25oC、85oC、125oC三個溫度進行。並提出一創新的做法，以功率轉換的方式，考慮電壓、電流及溫度，提供AC電路的CHC壽命計算。經實驗後發現，以功率轉換的方式描述元件劣化情形與實驗數據相符。在DC應力測試中，以高溫及較高的應力電壓之下元件劣化較為嚴重。在AC信號應力測試中，則以較長週期的訊號之下元件劣化較為嚴重。我們成功地預測DC及AC情況下元件之壽命，其中在DC條件之下，劣化都較為嚴重。本研究重要性在於能清楚告知晶圓廠或積體電路設計者，使元件劣化至失效所需的總功率，並由元件壽命模型得知元件應用於交流電路時的壽命，可為產業縮短不少測試時間，提高工作效率。

關鍵字

熱載子；直流；交流；總功率；等能量轉換；元件壽命模型

並列摘要

It is well-known that hot-carrier (HC) reliability test is usually executed with constant voltage stress (CVS) to investigate MOSFET degradation in wafer foundry. Furthermore, the device lifetime (τ) is thus determined. It is a kind of acceleration test in order to shorten the tested time for evaluating the device yield. However, MOSFETs are always operated on AC mode in CMOS circuits. Thus, it is important to precisely find the suitable AC lifetime model for in-circuit devices. In this research, the tested devices were from 65 nm technology of United Micro-electronics Corporation (UMC). The device channel width/length (W/L) equal to 1/0.05 (μm/μm). Stress modes were set with DC and AC channel hot-carrier (CHC) conditions. All tests were conducted at temperatures of 25, 85, and 125oC. We propose a new way, power transform, that includes the voltage, current, and temperature, is used to find the AC lifetime of high temperature CHC. The DC and AC CHC test results show that the power transform model can describe device damage and is consistent with DC and AC stress data. In DC stress, the stress with the maximum stress voltage and the higher temperature causes the most severe device degradation. In AC stress, the stress signal with higher time period causes the most severe device degradation. We successfully predict device lifetime. Comparing the DC and AC lifetime prediction at operation region, all the results show AC CHC lifetime is better than DC CHC lifetime. The significance of this study is to clearly give wafer foundries and IC design houses the total transformed power (Ptotal) which causes device failure to understand the τ of in-circuit devices. It is not only to reduce the tested time, but also improve the work efficiency.

並列關鍵字

Hot-carrier ； DC ； AC ； total power ； lifetime model

參考文獻

[1.1] S. Y. Chen, C. H. Tu, J. C. Lin, P. W. Kao, W. C. Lin, Z. W. Jhou, S. Chou, J. Ko, and H. S. Haung, “Temperature effect on the hot-carrier induced degradation of pMOSFETs,” IIRW Final Report, 2006, pp. 163-166

[3.2] S. Y. Chen, C. H. Tu, J. C. Lin, P. W. Kao, W. C. Lin, Z. W. Jhou, S. Chou, J. Ko, and H. S. Haung, “Temperature effect on the hot-carrier induced degradation of PMOSFETs,” IIRW Final Report, 2006, pp. 163-166

[1.4] C. Hu, S. C. Tam, F. C. Hsu, P. K. Ko, T. Y. Chan and K. W. Terrill, “Hot-electron-induced MOSFET degradation-model, monitor, and improvement,” IEEE Journal of Solid-State Circuits, vol. sc-20, no. 1, 1985, pp. 295-305.

[2.11] C. Hu, S. C. Tam, F. C. Hsu, P. K. Ko, T. Y. Chan and K. W. Terrill, “Hot-electron-induced MOSFET degradation-model, monitor, and improvement,” IEEE Journal of Solid-State Circuits, vol. sc-20, no. 1, 1985, pp. 295-305.

[1.2]. M. Song, K. P. MacWilliams, J. C. S Woo, “Comparison of NMOS and PMOS hot carrier effects from 300 to 77 K,” IEEE Transactions on Electron Devices, vol. 44, no. 2, February. 1997, pp. 268-276.

國際替代計量

以功率轉換研究65 nm nMOSFET之高溫熱載子交直流壽命

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